Fedora Linux

? The manpages for bash, chmod, and zenity

Chapter 5. Package Management

One of the advantages of Fedora is the huge amount of software available for it. Finding, installing, updating, and removing this software can be a daunting task, simply due to the amount of software available.

Fortunately, Fedora uses a software management system called RPM Package Manager or simply RPM (formerly RedHat Package Manager). RPM rolls all of the programs, scripts, documentation, configuration files, and data used by a piece of software into a single file called a package . The package also contains metadata describing the package, license, maintainers, and the packages upon which the package depends (for example, a KDE application will need other components of the KDE system to operate).

What RPM doesn't provide is dependency resolution : the ability to automatically resolve dependency issues. However, the yum system builds on RPM to provide this capability, automatically searching external repositories to find needed packages and install them automatically.

In this chapter, the sections Lab 5.1, 'Querying the Package Management Database' and Lab 5.2, 'Installing and Removing Software Using RPM' deal with individual package management from the command line. If you want to go directly to the simplest and most comprehensive way of managing software packages, skip to Lab 5.3, 'Using Repositories.'

5.1. Querying the Package Management Database

The RPM package management database is an essential source of information about your system. The database is created when the system is installed and is updated whenever packages are added or removed.

As RPM packages are installed on your system, the metadata for those packages is stored in a database that can be queried. If you have a mystery file on your system and want to know where it came from, or want to know which version of a package is installed, or what a package does, an RPM query can answer your question in a few seconds.

5.1.1. How Do I Do That?

The rpm program provides access to the RPM database. The -q option enables query mode.

The default query takes a package name and tells you whether it is installed and, if so, which version is installed:

$ rpm -q selmyscan
package selmyscan is not installed
$ rpm -q httpd
httpd-2.0.54-10.2

More advanced queries use two different sets of arguments: one to control which packages are reported in the output, and one to control what is reported about the selected packages.

Table 5-1 describes the most commonly used options for selecting packages.

Table 5-1. RPM query options for package selection

Option	Description
-a	Selects all packages.
-f file	Selects the package that installed file.
-g pkggroup	Selects the packages that belong to pkggroup (such as Applications/Productivity).
-p pkgfile	Selects the uninstalled RPM package file pkgfile, which can be a local filename or an HTTP or FTP URI. Information is retrieved from the package file instead of from the RPM database.
--triggeredby package	Selects packages that have scripts that are triggered by the installation or removal of package. For example, a mail-client package may have a script that changes its configuration if the local mail server is changed from sendmail to postfix.
--whatprovides capability	Selects packages that provide a certain capability, such as the ability to run perl scripts.
--whatrequires capability